Fowlpox virus is unique among the poxviruses in that it has by far the highest lipid content. Not only does the lipid fraction contain a significant amount of cholesteryl ester, but very surprisingly, a high percentage of squalene as well. In contrast squalene is absent or present only in trace amounts in the normal host cell. The proposed experiments are designed to take advantage of the decided shift of the infected cell towards sterol biogenesis. Initially, the identification of the lipid fraction of fowlpox virus will be completed. In particular, the minor sterol and the phospholipid components will be examined in detail. Experiments are also planned to investigate how poxvirus infection alters host cell lipid metabolism. Odd and even chain fatty acid synthesis and reactions in the mevalonate yields squalene yields cholesterol yields cholesteryl ester pathway will be followed through determination of the fate and rate of transformation of supplied radioactive lipid precursors to normal and infected cells. Finally, attempts to influence infectivity of the fowlpox virus particle by modification of the virus lipid coat will be made. It is anticipated that the virus lipids will be altered through administration of drugs affecting lipid synthesis.